Predation rate of Podisus nigrispinus (Heteroptera: pentatomidae) as inflenced by the density ofAlabama argillacea (Lepidoptera: noctuidae) and cotton plant age

Abstract

The predation rate of fifth instar nymphs and females of Podisus nigrispinus (Dallas) was evaluated at low and high threshold control levels for Alabama argillacea (Hüebner) larvae, in 20, 40, and 60 day old cotton plants. Five cotton plants were caged in the field with one and three A. argillacea larvae per plant and one nymph or one female of the predator. Nymphs and adults of P. nigrispinus preyed a higher number of larvae under conditions of high density of larvae and small leaf area in young cotton plants. Nymphs and adults of the predator restrained plant defoliation bellow threshold control levels at both infestation levels and plant ages of 20 and 40 days, compared to that of plants without the predator and 60 day old plants. Under laboratory conditions, adults of P. nigrispinus preyed more A. argillacea at high density (.3 and 0.4 larvae per day and total, respectively). P. nigrispinus weight gain was affected when they were maintained in plants at more advanced development stages, in both tested densities of A. argillacea larvae under field conditions and at density of one larva in labo­ratory. Additional keywords: biological control, cotton leafworm, Gossypium hirsutum, stinkbug predator.